nixCraft 🐧The website “Keep Android Open” is an initiative to protest and advocate against a new policy by Google which bans sideloading apps. The goal is to pressure Google to reverse or modify this policy to protect the open nature of the Android platform and the ability to sideload or use 3rd party app stores without excessive restrictions https://keepandroidopen.org
Andreas Albrecht@nixCraft The feedback and public consultation periods in the EU ended on October 24. The cited website doesn't reflect this yet.
You can still send feedback to Google. I doubt it will change their position.
Alternative Android-based OS are good, but they also face the restricted market access to the needed developer resources (see their development blogs etc. for more info). Therefore, consumer protection and competition authorities are the right bodies to be addressed here.